Photosynthesis Lab
How does intensity and wavelength of light affect photosynthesis?
Hypothesis: I predict that the black paper stopped photosynthesis and the see through paper doesn't stop photosynthesis. Also that black paper decreases intensity and clear paper increases intensity and it absorbs more light than usual. Black paper has a longer wavelength while clear paper has a shorter wavelength. Black paper decrease in intensity because it blocks all light so photosynthesis can't occur. Also for the green and red paper more photosynthesis occur while blue decreases in photosynthesis.
Materials
scissors
black construction paper
potted plant
tape
blue, red, and green cellophane
5 large test tubes
glass-marking pencil
forceps
400-mL beaker
5 petri dishes
iodine solution
paper towels
Procedure
1. Cover 2 leaves with black and colored cellophane paper and one untreated
2. Wait 2 days than ans
3. Cut off leaves that are covered and the other that is not
4. Then put leaves in test tube and make sure you label them
5. Take out chlorophyll by putting test tube in boiling alcohol
6. Rinse in water and put it on petri dish
7. Then put lots of iodine on each leaf
8. Wait a little bit and put it on a paper towel.
9. Record data and give numerical value to colors
Test Color change Numerical Value
Black paper brown-green 4
Cellophane brown 3
Red paper black 4
Green paper brownish-orange 2
Original green 1
Analysis/Conclusion
The black paper is lighter than uncovered leaf and decreased in intensity and increases in wavelength. No sunlight occurred with the black paper. The clear paper increases in wavelength and decrease in intensity. The black paper has less photosynthesis happening and because of that which decreased the amount of starch. Red paper is darker than untreated leaf. Green has same color as untreated. Finally blue is lighter than untreated and red is darker than green. This is different than what we expected because we thought red was going to be similar to black and green was going to be lighter than red and black paper. I am surprised because we labeled everything correct and didn't mix up any of the leaves. Many variables were uncontrolled though; like the amount of sunlight and the health of the plants health and age and size of leaf.
Reflection
I found this lab interesting because of the color changes based on the different paper you put on the leaf. Also I liked how we extracted all the chlorophyll from the leaves by putting it in a test tube and boiling it in boiling alcohol. I think me and my partners worked okay together because we were off track but we still managed to finish. Next time I would record more precise data and really observe the color changes of the leaves.